CVE-2007-6192 in NetScaler
Summary
by MITRE
The web management interface in Citrix NetScaler 8.0 build 47.8 uses weak encryption (XOR of unpadded data) to store credentials within a cookie, which makes it easier for remote attackers to obtain cleartext credentials when a cookie is captured via a known-plaintext attack.
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Analysis
by VulDB Data Team • 08/01/2019
The vulnerability identified as CVE-2007-6192 affects the web management interface of Citrix NetScaler 8.0 build 47.8, representing a critical security flaw in credential storage mechanisms. This issue stems from the implementation of weak encryption techniques within the cookie-based authentication system, where credentials are stored using a simple XOR operation against unpadded data. The flaw demonstrates a fundamental misunderstanding of cryptographic principles and secure credential handling practices, as the XOR encryption method provides minimal protection against determined attackers. The vulnerability specifically impacts the web management interface, which is a critical component for system administration and configuration management, making it an attractive target for malicious actors seeking unauthorized access to network infrastructure.
The technical implementation of this weakness involves the application of XOR encryption without proper padding mechanisms or cryptographic strength, resulting in predictable patterns that can be exploited through known-plaintext attacks. When users authenticate to the NetScaler management interface, their credentials are packaged into cookies and encrypted using this vulnerable XOR algorithm. The lack of proper padding means that attackers can analyze the encrypted cookie values and potentially reverse-engineer the original credentials through pattern analysis and statistical methods. This vulnerability directly relates to CWE-327, which addresses the use of weak encryption algorithms, and CWE-310, which covers cryptographic issues in data protection. The implementation violates fundamental security principles outlined in NIST SP 800-63 and other cryptographic standards that mandate the use of strong, well-established encryption methods for sensitive data protection.
The operational impact of this vulnerability extends beyond simple credential theft, as successful exploitation can lead to complete compromise of the Citrix NetScaler appliance and potentially the entire network infrastructure it protects. Attackers who capture authentication cookies through network sniffing or other means can easily reconstruct cleartext credentials, enabling them to perform administrative functions, modify configurations, and gain unauthorized access to protected resources. The vulnerability is particularly dangerous because it affects the web management interface, which typically requires elevated privileges and provides access to critical network controls. This represents a significant risk to organizations relying on NetScaler appliances for load balancing, application delivery, and security services, as compromised management interfaces can result in complete system takeover and data breaches. The threat landscape for this vulnerability aligns with ATT&CK technique T1566, which covers credential harvesting through phishing and network sniffing, and T1078, which addresses valid accounts usage for persistence.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to patched versions of Citrix NetScaler software, implementing network segmentation to isolate management interfaces, and deploying additional authentication layers such as two-factor authentication. The recommended approach involves applying the official Citrix security patches that address the encryption weakness and implement proper cryptographic standards for credential storage. Network monitoring should be enhanced to detect and alert on suspicious cookie capture activities, while access controls should be tightened to limit management interface access to trusted networks only. Security teams should also consider implementing certificate-based authentication and disabling the vulnerable web interface when possible. The vulnerability serves as a reminder of the importance of proper cryptographic implementation and the dangers of relying on homegrown or weak encryption schemes in security-critical applications. Regular security assessments and penetration testing should be conducted to identify similar weaknesses in other network infrastructure components, as this vulnerability demonstrates how seemingly minor implementation flaws can result in catastrophic security consequences.